Sometimes used interchangeably, taxonomies and controlled vocabularies are controlled lists of terms used to organize information. A controlled vocabulary is "an organized arrangement of words and phrases used to index content and/or to retrieve content through browsing and searching." (Harpring). Controlled vocabulary can be used in any industry that collects and uses information, such as academic research, libraries, corporations, governmental organizations, etc. Common types of controlled vocabularies include term lists, authority files, and thesauri.

Because controlled vocabularies require the use of predefined terms, they can be challenging to adopt and apply, but using controlled vocabularies during data or metadata creation supports consistency and accuracy. There are well-established vocabularies for personal and corporate names, geographic names, topics, concepts, resource types and genres, and languages.

Sources:

Patricia Harpring. "What Are Controlled Vocabularies?" in Introduction to Controlled Vocabularies. 

Heather Hedden. "Taxonomies and controlled vocabularies best practices for metadata" in Journal of Digital Asset Management (Oct 2010, vol. 6, no. 5) 

The are many types of controlled vocabularies from simple term lists to complex machine-readable ontologies. A few of the most commonly used controlled vocabularies are listed below. Understanding the type and scope is useful when selecting appropriate controlled vocabularies for projects.

Term Lists

A term lists, sometimes called a pick list, is the simplest type of controlled vocabularies. To create a term list, an agreed upon list of words and/or phrases is developed to identify a specific characteristic of a person, event, object, or other "thing". To use a term list, the user must select a term identified in the list. There are no synonyms or related terms identified; it is just a simple list of terms. Term lists are usually best when there are not a lot of terms needed, such as lists of file formats or object types.

Authority Files

The next level of complexity in controlled vocabularies is the authority file. Like term lists, authorities files provide a consistent list of terms to describe different kinds of resources, but also include cross-references from variant or alternate terms. Authority files often include other contextual or biographical information to assist users with disambiguation. Providing the preferred term, along with alternate versions provides more context for the metadata creator. Additionally, alternate and variant terms could be indexed in databases, allowing users to find the appropriate resources, even if they do not know the proper term. Authority files are commonly used to identify proper forms of names, such as in the Library of Congress Name Authority File.

Taxonomies

In recent years, the term "taxonomy" has become a sort of generic term for any kind of controlled vocabulary, particularly in business applications. From an Information Sciences perspective, a taxonomy is a hierarchical classification or categorization system in which "all the terms belong to a single hierarchical structure and have parent/child or broader/narrower relationships to other terms.²" Taxonomies allow for classification according to a pre-determined system. In comparison to authority files, which have preferred terms and variant terms, a taxonomy also includes a hierarchy, designating both broader and narrower terms. 

Thesauri

A thesaurus is a kind of dictionary represents all the concepts for a specific domain in a consistent manner and labels each concept with a preferred term. Like the previously described examples of controlled vocabularies, thesauri contain preferred terms, variant terms, and broader and narrower terms. Additional, the thesaurus also includes related terms, which may or may not be part of the same hierarchical structure of the term. A commonly used thesaurus for describing art, architecture, and material culture objects is the Getty Art & Architecture Thesaurus.For instance, the Getty Art & Architecture Thesaurus entry for "cellular telephones" gives alternate terms such as mobile phone in English, Handy in German, and shǒu jī in Pinyin Chinese. The entry also provides a definition and a hierarchical categorization of the term.

General Purpose:

• Names
  • Library of Congress Name Authority File (LCNAF) includes names for titles, persons, groups, and geographic locations.
  • Virtual International Authority File (VIAF) combines name authority files from national libraries and research institutions around the world.
• Concepts, Objects, Topics, etc.
  • Library of Congress Subject Headings (LCSH) is a massive list of terms used to describe resources of various formats.
• Languages
  • ISO 639-2 Codes for Representation of Names of Languages provides two and three letter codes for identifying language.

Sciences:

• AGROVOC  Multilingual Agriculture Thesaurus is used in agriculture and food science, including controlled terms in nutrition, fisheries, forestry, environment etc.
• International Classification of Disease (ICD) is the international standard to identify diseases and health conditions for clinical  and research purposes. 
• Medical Subject Headings (MeSH) is created by the National Library of Medicine for indexing journal articles and books in the life sciences.
• NASA Thesaurus covers aerospace engineering, the natural space sciences (astronomy, astrophysics, planetary science), Earth sciences, and the biological sciences.
• National Agricultural Library Thesaurus is a list of terms in English and Spanish for research in agriculture.

Social and Behavioral Sciences:

• American Folklore Society Ethnographic Thesaurus contains headings and terms in folklore, ethnomusicology, ethnology, and related fields.
• Data Documentation Initiative (DDI) Controlled Vocabularies is used with DDI in the fields of social sciences, behavioral sciences, economics, and health sciences.
• Geographic Names Information System (GNIS) has information about physical and cultural geographic features in the United States, associated areas and Antarctica.
• Getty Thesaurus of Geographic Names Online (TGN) includes names, descriptions for historical places, archaeological sites, and physical features.
• UNESCO Thesaurus is the list of terms used in education, culture, natural sciences, social sciences, human sciences, communication and information.

Arts and Humanities:

• Getty Institute Art and Architecture Thesaurus Online (AAT) consists of terms that may be used to describe art, architecture, decorative arts, material culture, and archival materials.
• Getty Institute Union List of Artist Names (ULAN) includes the names of individual artists, groups, and art-related institutions.
• Cultural Object Name Authority (CONA) compiles titles, attributions, depicted subjects, and other metadata about works of art, architecture, and cultural heritage, both extant and historical, physical and conceptual.
• Getty Thesaurus of Geographic Names Online (TGN) includes names, descriptions for historical places, archaeological sites, and physical features.
• Library of Congress Thesaurus for Graphical Materials (LCTGM) consists of over 7,000 subject terms and more than 650 genre/ format terms used to describe visual materials.
• Rare Books and Manuscripts Section (RBMS) Controlled Vocabularies provide standardized vocabulary for retrieving special collections materials by form, genre, or by various physical characteristics that are typically of interest to researchers and special collections librarians, and for relating materials to individuals or corporate bodies.